Implantable tissue stimulator with a porous anchoring enclosure

ABSTRACT

An implantable cardiac pacer housing comprising a fabric panel having suture flaps extending from a central compartment receiving the power supply and circuit container of a plug connected pacer, a port being provided in said compartment to pass connectors on the container for mating with the plug of a flexible probe and a flap enabling removal and replacement of the container.

Waite States Patent Mansfield [54] TMPLANTABLE TISSUE STIMULATOR WIITH APOROUS ANCHORING ENCLOSURE [72] Inventor: Peter B. Mansfield, 159Washington Ave., Needham, Mass. 02192 [22] Filed: June 22, 1970 [21]App]. No.: 48,379

[52] US. Cl ..128/4l9 P [51] int. C1. ..A6ln H36 [58] FieldoiSearch..128/418,419 P,419 11,421, 128/422 [56] References Cited UNITED STATESPATENTS 3,474,791 10/1969 Bentov ..128/4l9 P 3,253,595 5/1969 Murphy,Jr. et a1. 128/419 P 3,486,506 12/1969 Avphan 128/419 P 3,244,174 4/1966Wesly et a1. ..128/418 Auphan ..128/419 P [151 3,683,933 51 Aug. 15,1972 OTHER PUBLICATIONS Cammilliet al. Surgical Forum," 1966, pp. 165-168 Morris et al. Annals of the New York Academy of Sciences," Vol. 167,Art. 2, Oct. 30, 1969, pp. 987- 994 Primary Examiner-William E. KammAtt0rneyRich & Ericson [5 7] ABSTRACT An implantable cardiac pacerhousing comprising a fabric panel having suture flaps extending from acentral compartment receiving the power supply and circuit container ofa plug connected pacer, a port being provided in said compartment topass connectors on the container for mating with the plug of a flexibleprobe and a flap enabling removal and replacement of the container.

4 Claims, 5 Drawing Figures Patented Aug. 15, 1972 3,683,933

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[3 M5 I I I INVENTOR PETIER B. MANSFIELD EL 0 BY M L@ FIG. 4

ATTORNEYS IMPLANTABLE TISSUE STIMULATOR WITH A POROUS ANCHORINGENCLOSURE My invention relates to cardiac pacers, and particularly to anovel implantable housing for the same.

Considerable progress has been made in the development of cardiac pacersfor use in supplying electrical stimulatingpulses to regulate themammalian cardiac function in the absence of naturally occurring pulses.For optimum prosthetic efficiency, it is desirable that such devices beentirely implanted in the body of the host. It is usually desired toapply the stimulating pulses directly to the heart, and for example, tothe myocardium. On the other hand, the size of the basic elements usedfor producing the stimulating pulses, namely, the power supply and thepulse generating circuit ener' gized thereby, require a natural orincised body cavity larger than is available directly adjacent theheart. Thus, it is the practice to implant the power package, containingthe power supply and pulse generating circuit for the pacer, in thenearest convenient location, and to connect it to a stimulatingelectrode or electrodes at the heart by means of a flexible insulatedcable. The power package is allowed to rest in the selected body cavity.Since the power package is of significant size and weight, trauma mayresult from movements of the host, or simply from friction incidental toslight shiftings about incident to normal respiration and cardiacfunction. The object of my invention is to facilitate the anchoring ofthe power package of a cardiac pacer without interfering with itselectrical function.

Briefly, the above and other objects of my invention are attained by anovel pacer support comprising a fabric body formed to provide suturepanels for attachment to tissue at the wall of the cavity in which thepacer is to be implanted. The fabric body is further formed with areceptacle for receiving and holding the pacer power package whilepermitting the exterior of the package to serve as a return electrodefor the pulse generating circuit, and admitting electrical andmechanical connections to a flexible probe for connecting a remotestimulating electrode to the power package. In practice, the powerpackage, in its support, is implanted in the selected cavity, and theelectrode probe assembly is electrically and mechanically connected tothe power package. The suture panels of the support are then sewn to thetissue wall of the cavity, and the surgical entry is closed. Thereafter,scar tissue growth occurring in and about the fabric support anchors thepackage to the wall of the cavity, supplanting the sutures as they areabsorbed by the body. This tissue growth process does not interfere withthe electrical return path provided by the metal housing of the pacerpower package.

The manner in which the apparatus of my invention is constructed, andits mode of operation, will best be understood in the light of thefollowing detailed description together with the accompanying drawings,of a preferred embodiment thereof.

In the drawings,

FIG. 1 is a schematic orthogonal sketch of a pacer power packageprovided with a support in accordance with my invention;

FIG. 2 is a schematic elevational sketch of a complete pacer, togetherwith the support of my invention, with parts shown in cross-section andparts broken away; I

FIG. 3 is a schematic plan view of the apparatus of FIG. 2, with partsbroken away;

FIG. 4 is a schematic cross-sectional elevational sketch of a portion ofthe apparatus of FIGS. 2 and 3, taken substantially along the lines 4--4in FIG. 3, with parts omitted and parts broken away; and

FIG. 5 is a schematic plan view of a fabric panel adapted to form asupport in accordance with my invention.

Referring to FIG. 1, I have shown the power package of a pacer enclosedin a fabric support and container generally designated 1. The powerpackage may be of any conventional construction, in accordance with myinvention in its broader aspects, but preferably comprises a relativelythin, flat generally rectangular metal case 3, of stainless steel or thelike, forming a sealed conductive enclosure about a pulse generatingcircuit, to be described briefly below. Protruding from and electricallycontinuous with the -case3 are a support post 5, a flange 7 tapped andthreaded to receive a connecting screw, and an insulated connector post9. The post 5, flange 7 and the exterior portion 11 of the connectorpost 9 may be of stainless steel or the like, welded to or otherwiseformed integral with the case 3.

As best shown in FIG. 4, the metal case 3 encloses a battery 13connected between the case and a conventional pulse generating circuit15. The pulse output circuit extends between the case 3 and an activeoutput lead 17. The lead 17 extends through the post 11, and is spaced,sealed to and insulated from the post 11 by means of an intermediateglass-to-metal seal 19.

With reference to FIGS. 2, 3 and 4, the active output lead 17 isconnected to an exposed body contacting stimulating electrode 21, ofstainless steel or the like, over a flexible conductor 23. The conductor23 preferably comprises a helical coil of wire, and most preferably aconstruction comprising two parallel wires wound into parallel congruentconcentric contiguous helices in the manner shown and described incopending US. Pat., application Ser. No. 41,980 filed by Jean E.Bellerose on June 1, 1970 for Flexible Electrical Probe and assigned tothe assignee of this application.

The conductor 23 is covered and insulated by a layer 25 of siliconerubber or the like, and extends from the electrode 21 to a terminationwithin the body of an insulating plug 27, also of silicone rubber or thelike. The plug 27 may be bonded to or otherwise formed integral with theinsulating layer 25.

As schematically indicated in FIG. 4, the lead 23 is electrically andmechanically secured within the plug 27 to a contact 29 adapted toengage the lead 17 when the plug is engaged with the housing 3. Asshown, the plug 27 is formed with recesses cooperatively receiving theposts 5 and 11 to seal the latter and form a firm mechanical connection.The plug is secured to the housing by means of a screw 31 engaging thethreaded flange 7 and received in suitable recesses formed in the plug27 as shown in FIG. 4.

The pacer support 1 may be made from a fabric panel of the generalconfiguration shown in FIG. 5. Preferably, the panel is made fromrelatively open machine knitted mesh, such as MIERSILENE polyester fibermesh made and sold by Ethicon, Inc. of Somerville, New Jersey, andmanufactured from DACRON polyester fiber. Comparing FIGS. 1, 2, 3 and 5,the pacer support comprises a pairof suture panels 33 and 35 at thesides of a box-like container formed by a back panel 37, a top panel 39,a bottom panel 41, a front panel 43, and two side panels 45 and 47. Thetop panel 39 is provided with one or more apertures such as 49 to passthe connector posts 5 and 9 and the flange 7.

The side panels 45 and 47 are each secured to the front panel 37, bottompanel 41 and top panel 39 by suitable means, as by sewing with DACRONthread, in the same manner illustrated in detail for the panel 45. Asshown, the panel 45 is secured to the bottom panel 41 by a seam 51, tothe back panel 37 (at its juncture with the suture panel 33) by a seam53, and to the top panel 39 by a seam 55. The seam 55 is sewn afterinsertion of the case 3. The front panel 43 is then sewn to the toppanel 39 to form a seam 57, and a seam 59 corresponding to the seam 55is sewn to secure the side panel 47 to the top panel 39.

The case 3 is preferably encased in the support 1 before implantation.In general, the flexible probe comprising the cable 23, its insulatingcover 25, the electrode 21 and the plug 27 are implanted as one unit,and the case 3 and its support 1 are then implanted. Connection of theplug 27 to the case 3 is then made, and secured by installation of thescrew 31. The suture panels 33 and 35 are then sutured to the wall ofthe selected cavity, as by stitches 61, FIG. 2. As a result, theelectrode 21 is precluded from leaving the desired site for stimulation,as might occur if the case 3 were free to move in its assigned cavity.Tissue ingrowth occurring between the tissue wall to which the suturepanels are secured and the anchoring network provided by the strands ofthe fabric support assembly then proceeds, whereupon the support becomesfirmly secured to the body.

While designed for maximum operating life, the power supply for a pacerwill ultimately be exhausted, requiring replacement. The supportapparatus of my invention is especially well adapted to facilitate theprocess of replacement. Following a suitable surgical entry, the screw31 is removed, and the plug 27 disconnected from the case 3. An incisionis next made in the top panel 39 sufficient to permit the withdrawal ofthe case 3. A replacement case is inserted in the support 1, and the toppanel refastened with a few stitches. The plug,27 is then replaced, andthe screw 31 is installed. The support 1 remains anchored in the body,and thus serves as a permanent repository for the power supply package.

While I have described my invention with respect to the details of apreferred embodiment thereof, many changes and variations will occur tothose skilled in the art upon reading my description, and such canobviously be made without departing from the scope of my invention.

Having thus described my invention, what I claim is: 1. An implantablebody tissue stimulator adapted to be anchored and stored in a selectedbody cavity, comprising:

a housing; means within said housing for generating electrical tissuestimulatin signals" and porous means su stantially totally enclosingsaid housing for securing it to living tissue and adapted to anchor itin place in said selected cavity by enabling body processes to interactwith said enclosing means, said means including flap means enablinglater removal and replacement of said housing without interfering withthe anchoring in place of said enclosing means.

2. The stimulator of claim 1 wherein:

said stimulator is a cardiac pacer.

3. The-pacer of claim 2, wherein:

said housing is conductive and effectively provides a terminal for anelectric circuit; and

said enclosing means is formed from a mesh and includes a gauze suturepanel for securing said enclosed pacer to living tissue.

4. The pacer of claim 3, wherein:

said enclosing means includes a set of flaps sewn together to form a bagfor receiving and retaining said housing; and

said suture panel includes a pair of flaps sewn to opposite sides ofsaid bag for suturing to living tissue.

1. An implantable body tissue stimulator adapted to be anchored andstored in a selected body cavity, comprising: a housing; means withinsaid housing for generating electrical tissue stimulating signals; andporous means substantially totally enclosing said housing for securingit to living tissue and adapted to anchor it in place in said selectedcavity by enabling body processes to interact with said enclosing means,said means including flap means enabling later removal and replacementof said housing without interfering with the anchoring in place of saidenclosing means.
 2. The stimulator of claim 1 wherein: said stimulatoris a cardiac pacer.
 3. The pacer of claim 2, wherein: said housing isconductive and effectively provides a terminal for an electric circuit;and said enclosing means is formed from a mesh and includes a gauzesuture panel for securing said enclosed pacer to living tissue.
 4. Thepacer of claim 3, wherein: said enclosing means includes a set of flapssewn together to form a bag for receiving and retaining said housing;and said suture panel includes a pair of flaps sewn to opposite sides ofsaid bag for suturing to living tissue.